T-M50 / T-M50 ASME Service manual
Ver. 1.05
22
CONFIDENTIAL
10-8. Flow sensor
Unit Part #
#421
AOS Part #
EKH33
Checkpoint
H2
Function
Detects and measures water flow rate using a spinning impeller and magnetic
pick-up.
Failure event
Unable to detect or measure any water flow rate.
Effects on the water
heater if flow sensor
fails
Ignition sequence does not start (water heater will not initiate any operation)
Error codes when the
flow sensor fails
441 (only within Easy-link and Multi-unit systems)
Diagnostic
1. Visual inspection: connection / breakage of wires and/or debris on impeller.
2. Check voltages: proper range of values shown below.
Red - Black
4.0 to 5.5 VDC (Input)
Color/Number of wires
White(+)-Black(GND)
1 to 4 VDC (pulse)
1,200 pulse / min (more than 20 Hz)
Water IN
Water OUT
7-7/7” (200mm)
7-1/8” (30mm)
2
”
(5
0m
m
)
Water IN
Red
White
Black
